What was the minimum level of knowledge or skills required to participate in the WordPress project?

To participate in a WordPress project, basic knowledge of PHP is required, as WordPress is built on this language. You need to be able to work with themes and plugins, understand the structure of WordPress templates, know the basics of HTML and CSS for layout, and have an understanding of working with the MySQL database. Skills in managing the WordPress admin panel and understanding the principles of CMS operation are also important. For a junior level, basic PHP knowledge and the ability to configure themes are sufficient; for middle level, the ability to create custom plugins and work with the WordPress API is required.